The invention relates to devices, methods, and systems that employ interferometry to form images such as sonar imagers, radio telescopes, flow sensors, seismic monitors, etc. More particularly, the invention relates to techniques amenable to noise abatement, ruggedization, and various other benefits that flow from the modularization of components of an interferometric system.
Many interferometric receivers require high-channel count arrays, which enable the user or an autonomous system controller to make precise angular measurements for long-range detection, imaging, object classification, obstacle avoidance, etc. The operating frequencies can vary between a few Hz for seismic applications to many Megahertz or Gigahertz for ultrasound and radio systems. The sensors are usually arranged in an array in order to improve the signal to noise ratio for better detection. In such an array, the receiver hardware must be replicated for each channel. Since the number of array elements can vary from a minimum of four to several thousand, the cost for the receiver hardware can be a real burden. Furthermore, in order to perform the additional operations required for detection, for example: beam forming and multi-beam processing; each sensor output must be connected to a central signal processor. Depending on the number of array elements, this can create a serious wiring burden. Finally, since the sensors detect analog signals while the central processing unit operates in the digital domain, each channel must be equipped with a high-resolution analog-to-digital converter (ADC). The complexity of these systems limit the ability to provide for upgrades and modifications and render repairs expensive.
Therefore, there is a need for a scalable/modular imaging system.
Briefly, according to an aspect of the invention, a modular interferometric imaging system includes a sensor array that senses a physical parameter and provides a plurality of first sensor array output signals indicative thereof. An analog die receives the plurality of first sensor array output signals, and digitizes and modulated each of the first sensor array signals to provide a plurality of digitized signals. A digital die receives the plurality of digitized signals to provide a plurality of received digitized signals, and demodulates the plurality of received digitized signals to provide a plurality of demodulated digitized signals indicative thereof. A processor receives and processes the demodulated digitized signals to provide an imaging system output signal.
Integrating certain components in modular units that can be physically separated from the receiver hardware provides a scalable and modular system architecture. This has certain benefits in terms of wiring interconnects, modifiability, system expansion, ruggedness, and others. For example, separating the sensors from the electronics in oil exploration, where the sensors are large, reduces the physical size of the unit and renders it more portable. In medical imaging, portable units are needed for emergency technicians to image people at the scene, transmit the data to a computer for processing and finally to a doctor to make immediate decisions on life threatening problems. In autonomous undersea vehicles, torpedoes, towed array and submarine sonar systems, the physical space is very limited. Consequently, the sensors are frequently isolated from the remaining electronics so that their output signals must be routed to a remote ADC. By modularizing the components and multiplexing the signal interconnects, the manufacture and modification of systems can be greatly simplified and the systems ruggedized. According to an aspect of the invention, analog conditioning and digital conversion are performed within each module so that interconnects are digital. According to another aspect of the invention, the signals may be multiplexed reducing the physical channel count for interconnection. Still another refinement may be the combination of multiple sensors in a single module that may be combined with multiple other modules to form arrays of arbitrary size.
In one embodiment, the required analog and digital operations are consolidated (e.g., encapsulated) within two monolithic circuits, dies A and B, respectively. These two chips form building blocks, each of which performs signal conditioning, automatic gain control (in conjunction with an external controller), analog-to-digital conversion, multiplexing and telecommunication functions. These tasks are performed before the signals are submitted to the central processing unit.
By assembling the signal conditioning circuitry, the anti-alias filter, the ADC and the signal multiplexing operation on a single analog die, which can physically be mounted onto the same structure as the sensors, the opportunities for signal corruption are significantly reduced.
The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood. With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.
These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.